Blood pressure is checked at every encounter with a medical professional because of its relationship to many health problems. This includes sleep disorders as well. Low blood pressure (hypotension) and high blood pressure (hypertension) indicate an imbalance in the way the body functions, giving doctors some clues as to why.

Before we can discuss how one’s sleep life can influence one’s blood pressure, it’s important to know what high blood pressure (hypertension) is and why it can be dangerous to your overall health.

What is hypertension?

This is another name for high blood pressure, more or less.

To be more specific, you can experience high blood pressure temporarily as the result of exercise, drinking a cup of coffee, or being in REM sleep. These brief changes in blood pressure are normal and don’t warrant concern by themselves.

However, if your blood pressure remains high—even when you are sitting calmly, enjoying a cup of decaf, or while sleeping in non-REM stages—this becomes an issue known as hypertension.

Hypertension is caused mostly by lifestyle choices such as smoking, drinking, substance use or abuse, high consumption of sodium, or being overweight.

It can also be a condition that is inherited or is caused by aging (such as menopause), or it can be the result of an untreated health problem, which includes sleep disorders.

Checking for hypertension

Blood pressure checks on a routine basis can uncover problems with hypertension. Here are the latest guidelines regarding blood pressure readings and hypertension:

Readings at or below 120/80 are consistent with normal blood pressure

Elevated blood pressure suggests an increase in the first number between 120 and 129, with the second number remaining under 80

Stage 1 high blood pressure (or, hypertension) is considered a reading between 130 and 139 for the first number or between 80 and 89 for the second number

Stage 2 high blood pressure is defined as a reading of 140 or more for the first number or of 90 or more for the second number

Critical hypertension (requiring a visit to the doctor immediately) is defined as a reading of 180 or higher for the first number and/or a reading of 120 or higher for the second number

[This Heart.org chart not only shows guideline levels, but also allows you to check the severity of your own blood pressure readings.]

Why the two numbers?

The first number (the systolic number) measures the maximum pressure occurring in the arteries during the contraction (tightening) of the left ventricle of the heart during a heartbeat. The heartbeat marks the time when the heart fills with blood. In a blood pressure reading of 120/80, the systolic pressure is 120.

The second number (the diastolic number) measures the minimum pressure occurring in the arteries during the relaxation of the ventricles after they’ve filled with blood. In a blood pressure reading of 120/80, the diastolic pressure is 80.

More concern is applied to the systolic readings because it indicates a higher risk for cardiovascular disease in people over age 50. Generally, systolic blood pressure rises gradually as a result of aging, which causes arteries to stiffen over time and collect plaques on their walls.

However, the diastolic reading shouldn’t be ignored, either. You can diagnose hypertension if the second number is higher than normal, as research shows that the risks for both stroke and ischemic heart disease increase with increases in diastolic blood pressure among people 40 and over.

As mentioned earlier, one of the things that can take place during sleep is temporary increases in blood pressure during REM (rapid eye movement) sleep. This is normal, a part of the sleeping process, and reflects the nature of REM sleep. After REM sleep stages are completed, the blood pressure should return to normal.

Our eight hours at night while asleep should provide our bodies with the opportunity to rest and recover; lower blood pressure over the majority of the sleeping period is the rule, not the exception. However, in people with hypertension, this is not a typical reality. Elevated or high blood pressure interferes with the body's dynamic healing processes during sleep, creating more stress on the cardiovascular system than is considered healthy.

Poor sleep health is caused by a number of problems: compromised overall physical or mental health, medications, poor sleep hygiene, and sleep problems, such as sleep disorders. Hypertension can frequently be the outcome of untreated sleep disorders and other sleep problems such as:

It’s not that hypertension causes these problems, but rather, it happens when you have these sleep disorders and leave them undiagnosed and untreated. They all contribute to fragmented sleep, in which sleep is frequently disturbed, which disrupts sleep architecture and leaves people feeling exhausted and unrefreshed in the morning. One sign of sleep fragmentation caused by a sleep disorder is excessive daytime sleepiness.

Could healthy sleep prevent hypertension?

It’s possible. A number of other causes for high blood pressure need to be considered, but simply getting enough sleep can help lower your risk for developing it or at last keep it from worsening.

Hypertension does not happen overnight, but is the result of the long-term elevation of blood pressure. Overall good health and well being (due to regular exercise, stress management, good health habits, a healthy diet, and other measures of good health) are not only preventative measures for lowering risks for developing hypertension, but also result in good sleep health.

Unfortunately, untreated sleep problems are especially linked to blood pressure problems in people who are otherwise healthy.

For instance, if you have sleep apnea (either obstructive or central, or a combination of both), and you don’t treat it, it can cause insomnia and prevent you from getting restful sleep. This ongoing loss of quality sleep is linked with hypertension.

In fact, simply not sleeping enough almost guarantees you’ll develop hypertension. Those who sleep only five to six hours a night are at higher risk for doing so.

Snoring and insomnia also lead to disrupted sleep, as do restless legs, circadian imbalances caused by working night shift, and the parasomnia known as RBD, in which sufferers literally act out their dreams while asleep. Elevated blood pressure is a result of nearly all of these sleep health problems.

If you are concerned about sleep problems or learn you have elevated or high blood pressure (or have both concerns), it's in your best interest to discuss solutions with your doctor. The good news? Hypertension and sleep disorders are all treatable by various means and can result in improvements to both blood pressure readings and to sleep (and overall) health and wellness.